Process of making paper



My 28 1940- D. k, FvnTTILLocl-lv 2,202,717

r'nocsss oF MAKING PAPER Filed March 20. 1936 lnvenTor.. Donod- K. PQI-1i loch bymwew @ma A y 50 rent` which Passau my za, 1940 l UNITED STATES PATENT ori-*ics* zanzara I raocsss or mmc raras. Donald 1L rettilinei, Boston, Mass., signor-:to

Pntlloch Inc., Boston, Mass., a col;-

Processes poration ot Massachusetts Application March 20, 1936, Serial No. 69,844 s calms. (ci. acs-21) This invention relates to the manufacture of 5.- filling vor loading material.

One' object of the invention is to provide an improved process oi making paper which not only results lin an increased bonding action between the cellulose fibre and any amylaceous 10. bonding material contained in the fibre-water It is generally agreed that cellulose libres yina n libre-water mixture normally have a'negative electrical surface charge, the intensity oi which 20 varies with different kinds oi'iibre and varying water 'conditions- It. that when amylaceous bonding material, such as starch in any of its various forms, yis added to fibre-water mixture the'bo'ndingkmaterial partl- 25 cles, whether in the nsoidai or in the. colloidal form, usually are negatively charged or carry negative electrical surface charges." when these conditions exist in a nbre-water I y mixture containing `amylaceousbending material 30 and from which paper is being made, the bonding -or cementing of the. starch particles to 'the cellulose fibre brings together two particles nor'- mally having the same-electrical charge, with the result that there is set up between such bonded 35 particles an electricalrepelling torce which tends todecr'ease the chemical-physical bonding action between the bonded particles.

One feature of the presentk invention relates to a novel' method of paper rnanuiactureby 40 ,which this repellins action between the cellulose libre and the starch particles, whether caused electrically or otherwise, may not only'be eliminated but may be which augmente the chemical- 45 physical bonding action andl thus makes 'a more perfect bond between the cellulose libres and the amylaceous bonding.material. 1 Thisresult is subiecting mentire-- water mixture to the action of an electrical curthe re action between the starch particles and the cellulose libre due tc their-normally havr ins the same electrical charge' and provides theelectrostatic bond above. reterredto. d 55 lIn clubic-water mixture containing Aelectrodes will'preferably be submerged is' also generally agreedv carrying a negative electrical charge.-

replaced by an electrostatic results in decreasing or' eliminating should have such a relation to the 4 andnpoqition or ythe electrodes and to the intensity 55 a'rosin alum size precipitate, or a rollin soap, or clay or other filling or loading material, the particles of which carry negative charges o! electricity, this same electrical treatment results in an electrostatic bonding action between the cel- 5 lulose ilbres on one hand and the rosin'size alum precipitates or the particles of clay or other illling or loading material so that the bonding or cementing of the rosin size precipitate and/or the clay or other lling'or loading material to the 10 cellulose bre may be accomplished without the use of chemicals to provide the bonding element 4having the positive surface charge.

According to one way of carrying out the invention I provide suitable oppositely-charged f electrodes which are so placed that-the ilbrewater mixture will flow over or by them. Such in the libre-water mixture but may have any location which will permit them to subject the ubre-water mixture to the desired electrical treatment.

-The electrodes may be provided with opposite in any suitable way, one convenient way being to connect said electrodes to and the other will be in the nature of a cathode The negatively-charged colloidsy in a. ilbrewater mixture, such as starch, clay, rosin alum size precipitate, etc., are much more active and faster moving in the mixture lthan the negatively-charged cell lose ilbres. As the fibre-water mixture ilowspast, by or over the electrodes I the rapidly movingl active negatively-charged colloids are attracted o r drawn towardthe positive electrodes or anodes much more rapidly than the slower moving cellulose nbre. The activa rapidly-moving colloids thatj contact with the 40 A positive electrodes become positively charged and are then discharged'irom the electrode as a gel-with a positive electrical surface charge.`

.When thus positively charged these colloids are -the negatively-charged cellulose because of their slugglshness, have not been attracted into contact with the positive electrodes, and as the positively-charged colloids t. contact .or unite with the negatively-charged vlibres the electrostatic bond above-referred to between the colloids and the fibres is set up.

In carrying out the inventinit is desirable that the rate of ilow. of the fibre-water mixture shape; size ciently long .to enable the tively-charged cellulose libres to be attracted to the time during the anodes in any appreciable amount. Thus the cellulose nbre. passes through the sphere .of

electricalv action charge of electricity changed from negative to positive, while such lchange is effected in the negatively-charged colloids because of their greater activity and freedom of movement.

'As the nbre-water over the electrodes the colloids which have thus received the positive charge have ample time `either to attach themselves to an inactive colloidl of rosin alum size precipitate, starch o'r clay to precipitate the combination, which has a Apositive electrical charge, on the negatively-charged cellulose, or else such positively-charged colloids have been attracted to the negatively-charged cellulose to form, in-eiect, a positively-charged surface to which a have not had their surface chargeA changed from negative to positive are attracted and bonded electrostatically.

yI havefound from microscopic examinations of paper containing starch that in a paper made from -a furnish: to,A which the starch has been added in suspensoidal or colloidal form by any of the customary -prior methods, the starch particles have a globular form, while in a paper made by the method herein disclosed, the starch particles have more of an egg-shape form, .which shows that Athe process herein described has had a marked eil'ect on the physical structure ofthe starch particles. Indications are that similar changes will take place in the rosin alum size precipitate particles due the practise of the a libre-water mixture from y It is known that such negatively-charged Present invention.

negatively-charged colloids, such as starch, clay, rosfn alum size precipitate, etc., will be effectively precipitatedby positive ions, other than hydrOsen ions, or by other posil tive colloids of higher chemical valence, and that Themost predominant negatively-charged ion in is' the 804 ion which results from the hydrolysis Y of alum added to the fibre-water mixture. 'I'hese S04 ions may be re buffering or neutralizing moved by the electrical treatment herein-de-l scribed, thereby facilitating the movement of the starch or rosin sizing lcolloids toward the anodes 4and Apromoting their electrostatic combination with the negatively-charg cellulose.

While electrolytic action change the pHvalue of a tion, we have found'that plexityI of'the chemical nature of, a libre-water mixture, v'such as thatoperations, the electrical treatment above referred to can be used pH -value thereof, which is contrary to the theory 76 of ordinaryionization.

The term pH value mixture, is a term indicating the concentration of the rhydrogen Y ions, which are positivelyf charged ions, withrespect to the hydroxylfions, whichwa're .negatively-chargedionsr without 'having its surfacemixture flows past, by or portion of the colloids which.

ions act as a buffer.

which paper is made nominally does notsimple chemicalv solu' because of the com' -throughor by the If,` for instance, the ilbre-water-inixture immeused .in paper-makingV oppositely-charged 1- to change or'control the 'A pH value of 'i indicates a balanced condition between the positively-charged hydrogen ionsand the negatively-charged hydroxyl ions, and hence al neutral condition; a pH value less then 'I indih cates an excess of the positively-charged hydrogen ions andan acid condition; while a pH value greaterethan 'l indicates an excess of the hydroxyl ions and an alkaline condition. 1v

Paper mill operations are usually carried out with an acid furnish, that is, a furnish having a pH value below 7, although 'some mills operate with Aa furnish having a neutral or even an alka.

line pH value.

Where rosin size is added to the fibre-waterY practise to precipitate and in order to secure the size on the cellalum is generally used mixture it is the common the size by adding alum, a 4 proper precipitation of lose libres an amount of which -lowers the pH value of the libre-waterv mixture sometimes as low as 4.5 or less, which iu-` dicates quite an acid condition.

It is well understood in the papermaking art that paper made from an acid furnish is subject to chemical deterioration and `the rapidity of such deterioration dependsto a considerable ex.

tent upon lthe degree of aciditylofthe furnish. It is, therefore, desirable to reduce the acidity and to raise the pH value of the nbre-water mixture before the point of paper formation and this is commonly done by adding alkaline chemicals to the'furnish.

My improved process provides which the pH value of the libre-water mixture can be raised and can be readily controlled with-f` out the use of chemicals for this purpose andentirely by the electrical treatment of the librewater mixture, although under certain conditions Supplement the elec'.

it may be advantageous to a method by trical treatment with chemical treatment as de-.-

scribedm Patent 15m-2,036,832, April-'1, 1936.

tive positivelyharged hydrogen ions. nbre-water mixture flows past or over the elec'- trodes and electrolyticaction takes place," therev reaction which drives the positively-charged.hydrogen ions to the negative will be a cataphoresis electrode or cathode from whence they discharge as hydrogen gas. In this way the amount of these active hydrogen ions inthe solution is decreased with a resultant elevationof the pH value, 'v

of the fibre-water mixture. l The hydroxyl ions are present "in the fibrethe low pHvalues sothat the electroiytic process expels from. the fibre-water tively-charged hydroxyl ions.'` From repeated observations I have made I nd that the b'rewater mixture develops'a de-y pH -'value in lpassing over.-

ed electrodes.v

d-iately before contacting the electrodes has pH values of from 4.3 to 4 6, ^.it will, immediately after sitely-charged electrodes, have an elevated p being found t'o be anode to the cathode.

My improved; process, `therefore,fr iroigiles electrical means for reducing thieydrogen ion mixture manyn more y positively-charged -hydrogen'ions than nega- ,.-Lcontacting with the' 'oppo'4 As stated 'above the pH valueof the nbre-water. i

- mixture is an indicationof the concentration' of -the hydrogen ions-and a v,libre-water mixture having a pH value of 4.5 has a large .excess-of. the at- 55 .water mixture in relatively small vquantities at l agulation and electrostatic cellulose nbre and concentration in the libre-water mixture. and thus raising its pH value. and byproperly controlling the intensity oi.' the electric current `iiowing from the anode to the cathode throush the nbre-water mixture it is possible to bring and maintain the pH value to 'any desired point.

.Theoretically there will be a maximum cobonding between the the amylaceous bonding material and/or sizing material 'and/or loading materialvat the effectiveI isoelectric point oi thenbre-water mixture, at vwhich point there is an electrical balance oi' the positive and negative charges on the ingredients oi.' the furnish and a resultant zero velocity to the/colloidal particles It is well known that different lcolloids and particles have diiierent and definite isoelectric points. Theoretically in a libre-water mixture containing many colloids and particles there would be many isoelectric'points dependent upon the isoelectrlcpoints of the constituent coiloids, or particles. Actually. experiments have shown that any deiinite nbre-water mixture has a dennite iective isoelectric point, which is preferably expressed as a composite result oi the l commingled-colloids and particles in the mixture and which also depends somewhat on the type or types of .cellulose fibre used in the mix. Hence different furnishes points, andrthese points; which can be readily determined by known methods, will vary with the V variation in cellulose and chemical constituents of the furnish.

For example, I have on made 'paper by this process ing pHl values of 4.9, 5.2,. which pH valuesv werediierent occasions with furnishes havthe mixture.

There are advantages in maintaining the ribrewater mixture at its effective isoelectric point and this may be readily done through thel practise of my improved process.`

As the eiiective isoelectric point oi the nbrewater mixture is approachedthe electric resistance of the mixture increases and at the effective isoelectric point the resistance is such that it is practically impossible 4 to force more current through mixture, and electric cataphoresis action practically ceases.l Any departure .irom the isoelectric point will reducev the resistance allowing more current to ilow'through thereby .causing I conducted in an attempt to regulate and mainl tain the pH value voi a vto the iso-electric point.

process, thereiore,lthe nbre-water mixturewill lbe automatically maintained at the isoelectric a renewal of the cataphoresis action which will result in bringing the nbre-water mixture back With my improved point and a ,stable electrical balance in the mixture is maintained, a result which is not possible where the pH value of the mixture is being controlled by the use of chemicals.

This-is shown by 'experiments which I have nbre-water mixture at its leffective isoelectric point by means of chemical additions; As the pH value of the fibrewater mixtureV increased or decreased towards the effective isoelectric point by the 'continuous addition of suitable alkalis or acids there was a the-librLe-water mixture to sensitive to the chemical marked ytendency of become increasingly reaction,'and as the ei'ieetive-isoelectric point was closely approached; the additionb or decrease oi'..carefully-coritroi1ed quantities 'of added chem- 75' .icals .caused extreme iluctuations in pH value,

' im attempt t0 bring it will have diiierent isoelectric 5.6, 6.4 and others, determined by known. methods to be the eiiective isoelectric points oi .in my invention to employ .any

having an effective isocontrolled addition of chemical, the pH value v would increase to 5.5 or 5.7, and then on subsequent caretul reduction of added chemical in back to 5.1, the pH value -would decrease sharply to 4.6 or 4.7. This process, therefore, provides for the making of paper in which there is an electrical balance between the constituents and one which is relatively free from galvanic paper static.

Ordinary paper-making operations are apt to result in ,the development of battery-like formations of particles having unbalanced electrical charges, the presence of which battery-like formations produces galvanic static in the sheet.

One vadvantage of my inates to a great extent the development of these invention isthat it elimbattery-like formations and the .consequent resultant. galvanic static so that a sheet of paper made in accordance with my invention will be relatively free The presence of apaper highlycharged with static electricity offers diiiiculty in subsequent conversion or use and gives a. paper characteristic which makes it less adapted for use in printing, coating, winding and cutting. larly-this istrue on paper machines equipped with sheet cutters on the dry end, as paper heavily charged with static does not lie flat underv the knives, but curls more or less and results in the production of unevenly .cut paper.

In addition to the diillculties to the cutting or converting paper machines, a further deteriorating eiiect occurs in paper which contains a. high chargeof static electricity. Such paper decreases in physical test upon ageing, due probably to the continual migration and .shifting of electrical charges which result in setting up galvanic and frictional electricity within the paper.

` The location in the libre-water ilow at which the libre-water mixture is subjected to this electrolytic action is not important although there which the electrolysis would take place wire itself.`

While I prefer to 'use a uni-directional current iorcharging the electrodes or for treating electrically the fibre-water mixture yet it is withwhether D. C. or A. C. o'r a combination of both, by which thev above-named results can be secured.

In the drawing I have illustrated diagrammatically some ways in whichthe invention may be carried out.l

making operation embodying the invention in which the paper-makingA wire constitutes one oi the electrodes.

Particualso be possible to carry out s the process by an arrangement according to' on the'y type of current,

llisa diagrammatic view of the papercharges of electricity. 'I'hese Fig. 2 illustrates the invention as applied to a cylinderI machine.

Fig. 3 illustrates another manner of carrying out the invention.

Fig. 4 is a section on the line 3 3, Fig. 3.

Fig. 5 is a plan view of the headbox I2 and one end of the wire Il showing the electrodes I3.

Referring iirst to Fig. 3, indicates a iiow box through which the fibre-water mixture iiows to the paper-making wire. Situated in this box are a plurality of electrodes. 2, 3, the electrodes 2 being anodes carrying positive charges of electricity and the electrodes 3 being cathodes carrying negative electrodes may be in the form of platesl arranged in parallel relation, the alternate plates being anodes 2 and the other it may be plates being cathodes 3. The plates are connected in a charging circuit with the anodes 2 connected l includes the usual ammeter 1, volt posi-tively charged,

to one side I of the circuit and the cathodes 3 connected to the other side 5 oi' they circuit. This circuit includes a suitable generatorfor generating uni-directional current and the circuit also' meter 3 and variable resistance 9. 'I'he circuit isalso illustrated as having a Areversing switch Il therein. When the circuit is operating the anodes 2 will be while the cathodes '3 will be negatively charged and there will be a flow of u current from the anodes to the cathodes through the libre-water mixture iiowing between the electrodes.

The rate of aow or the abre-water mixture. the

size ofthe 'electrodes and their dimension in the is passing through the tively-charged direction of ilow Ahave such a relation that during the time that any portion of libre-water mixture electliiied zone the more active negatively-charged colloids above-referred will be attracted to the positively-charged anodes and upon contact therewith will take a positive charge of electricityand then be discharged from the anodes as a gel. The negacelluloselibres, however. are so sluggish in their movement that they will be carflow box in relatively -receive any positive charge electrodes in the form ried bythe flowing movement ofthe libre-water mixture through and beyond the electrodes before they have time to be attractedinto contact with the anodes to any appreciable extent, and, therefore, as the nbre-water mixture flows lthrough the electrified zone the active colloids 'will be positively charged but the cellulose ilbre will not to any appreciable extent. As stated above, the :positively-charged particles of starch, rosin, clay or other material, which are discharged'from the anodes 2- become attracted to and unite with the negativelycharged cellulose libre to .produce the bonding eiiect above-described. In the operation oi' this device an important feature is to maintain such a relation between the rate of iiow of the fibrewater mixture, the size and position of the electrodes and the intensity of the electrical charge thereon, that while the more active negativelycharged colloids will be attracted to the anodes and thus become positively charged, the slower moving'cellulose 'fibre will pass through the elect ed zone irefore the libres in any appreciable a ount have time to become attracted to and contact with the anodes 2. In practicing the in-- vention I have secured successful results by using of plates which are longer than they are wide and' which are placedin the the lengthwise direction of the plates parallel to1 and using the current for an ordinary lighting become attracted tively charged 23 indicates close parallel relation with circuit for nsr'glng the` portunlty to'contect with relation to the rate of flow `that the active negatively charged colloids will` thereby come in contact with the positively `charged plates during the iiowof the libre-water lthe electriiled` zone while the sluggish cellulose fibres will not mixture through slower moving or electrodes in any appreciable amounts while they are ilowing through the electriiied zone. As the process is continued a deposit of electrodes I4 which are connected by a wire- |5 to a generator I6, theother wire 'I1 of the cirbe attracted to and to or contacted with theposi will gradually accumulate on the cathodes whichI e I cuit being connected to the couch roll |3 overwhich the wire Il-passes so that the wire Il constitutes the other electrode; With this construction it will be necessa A, of course, to insulate the wire and the breast 'roll I9 and couch roll I3, and the wire-carrying rolls 23. The operation of this 'embodiment is may constitute the anodes which is negatively charged. The operation of'the device is similar to that above-described. As-.the'

libre-water mixture |.3 flows vpast the anodes I3 tively charged and discharged while the more sluggish cellulose the fibre-water mixture gel colloids, starch, clay,

iiows onto the wire the cellulose libre.

the same as that abovedescribed In this embodiment the electrodes Il which are positively chargedand the wire constitutes the cathode resin alum precipitate, etc., will become eiectrostatically bonded to the y In Flg.- 2 there is shown a cylinder lmachine-- having' .the

a series of electrodes similar to the electrodes M in. Fig. 1 which are immersed in thetankadjacent the point where the librewater mixture is delivered thereto. These electrodes 23 and the cylinder 2| are connectedto the generator 23 through the wire connections 23, 23, the electrodes 23 constituting the anodes cylinder 2| operating in the vat 22.

and the cylinder 2| constituting thecathodes.v

The operation of the installation shown in Fig. 2 issimiiartothatinFigs. 1to3. As theiibrewater mixture iiows'past or through the electrodes 23 the more active colloids, clay, rosin alumsize normally negatively-charged,l become attracted to and contact with the anodes 23 and disc ed therefrom as a gel having positive charges of electricity. Such positively-charged colloids then become united to or bonded with the cellulose libre. which is negatively charged bymeans'of the electrostatic bond above-referred also it is desirable thatl to. In this embodiment the rate of ow of libre-water mixture past the electrodes 23 should. be such that the more actlvenegativ'ely-c ed colloids will have opand receive `their posisuch as starch, precipitate, etc., which are tive charge of electricity from the electrodes while the more sluggish cellulose fibre will pass between the electrodes Without receivingk posit tive charges therefrom.

I claim:

1. The method of making paper from brewater mixture containing negatively-charged colloidswhich consists in flowing the fibre-water mixture over electrically-charged anode and cathode electrodes and maintaining the fibrewater mixture in the electrified zone between becomes eiectrostatically bonded thereto.

2. The method of making paper'frmlibrewater mixture containing negatively-charged colloids and negatively-charged cellulose libre,

which consists in flowing the libre-water .mixturein contact with positively-charged electrode plates havingv their lengthwise direction in the direction of flow and maintaining the fibre-water mixture in the zone subject to the electrical action of said plates for a sufilcient time to permit .the negatively-charged colloids to b'e attracted to and contactwith said plates but insuilicient to permit the negatively-charged cellulose fibres to be attracted to said plates in any appreciable amount.

3. The method of treating flowing libre-water mixture 4containing -cellulose bre and colloidal particles having an electrical surface charge similar to that of the fibre, which method consists in flowing-the mixture past positively charged electrode plates which extend a considerable distance in the direction of flow and at arate of speed greater than that required for the cellulose iibre to be attracted to said plates but less than that required for the colloidal particles to be so attracted, whereby the colloidal particles are attracted tothe positively charged plates and thus become positively charged while the cellulose ilbres' flow past .the plate without being so 

